You will be using the outside curve filing for this technique for this. To do this, you will use your flat file. As the file moves forward, bend your wrist slightly and lift your elbow to follow the sharp edges of the side of the band. Use long strokes, and keep the file moving in a smooth continuous curve, slowly softening and rounding your sides.

You can use this technique to help smooth out and blending in your waves or to slim down, creating a very delicate looking band.